As used herein, transient document media is media that is suitable for use with transient printing technology, such as reusable paper. Thus, a printed transient document is a document that consists of transient document media. One type of printed transient document is a special type of reusable paper that is treated with a chemical capable of changing color when exposed to a light source or to a heat source. Such exposure of the transient ink to the source results in the creation of an image (e.g., text and/or graphics) that can last for a certain period of time (e.g., one or two days) before fading away and ultimately disappearing. Alternatively, a user can proactively erase at least a portion of the image on the printed transient document by exposing the printed transient document to a particular source such as a light source or a heat source.
With the emergence of printed transient documents, the same physical document can be used repeatedly over the course of multiple cycles of user interaction. By allowing a user to use the same physical document over and over again, a transient document based system enables the user to effectively reduce the amount of paper that would otherwise be used to print multiple copies of a document such as successive revisions thereof.
The use of transient documents is particularly effective for documents that need only be available for a limited time. For example, a user can print a non-final draft of a legal brief using transient document media. The user can subsequently print each successive revision of the draft on the same media before achieving the final draft. Once the final draft is completed, the user can print a copy of the final draft in a more permanent manner using regular ink on traditional paper, for example.
The use of transient document media for printing legal documents can provide an additional benefit in that such use prevents virtually any revision of each legal document printed using transient document media from being discoverable. This is because the text of each version of the document that is printed on the transient document media would disappear at a certain point, such as after a certain amount of time has passed or after the transient ink has been proactively erased by exposure to a light source or to a heat source, for example. The real estate and mortgage industries are other industries that can greatly benefit from the use of transient documents, as those particular industries often use a large amount of paper for multiple revisions of various types of documents.
However, there remains a need for effective permanence estimation and policy enforcement for transient document based systems. For example, while the use of transient document media can save paper and money, such use typically requires that users determine which documents should be printed using transient document media and which documents should be printed using traditional, permanent document media. These determinations can easily take up a user's time and disrupt the user's thought process, thereby resulting in a cost to his or her employer that is significantly less than optimal.